This application claims the priority of German Application No. 101 22 459.1 filed May 9, 2001, which is incorporated herein by reference.
This invention relates to an apparatus integrated in a fiber processing machine, such as a card, a cleaner, an opener or the like for fiber material such as cotton and chemical fibers. The fiber processing machine has roll cover elements associated with a rapidly rotating roll. Between the cover elements a plurality of openings are provided. A first opening serves for the discharge of foreign bodies, such as trash, seed fragments, leaf fragments and the like whereas a second opening which is arranged downstream of the first opening as viewed in the rotary direction of the roll, serves for discharging fiber material by an air stream.
German patent document No. 1 114 127 describes an apparatus in which the fiber tufts, freed from a preponderant part of foreign bodies, are brought on a doffer in the effective zone of an air stream which carries the fiber tufts to a screening drum separator or a pneumatic transport device. The doffer has a sawtooth-like clothing whose teeth are inclined in the direction of roll rotation so that the fiber web attached to the teeth is readily removed by the suction air stream. The air stream is drawn from the outside through a gap. It is a disadvantage of such a prior art construction that it is not possible to vary the air stream. An outlet opening for the foreign bodies in the cover for the doffer is not present because the fiber material on the doffer has already been substantially cleaned.
It is an object of the invention to provide an apparatus of the above-outlined type from which the discussed disadvantages are eliminated and which, in particular, makes possible a variation of the fiber-doffing air stream and also provides for an improved waste quality at an outlet opening.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the fiber processing machine includes a clothed roll entraining fiber material thereon; a roll cover circumferentially partially surrounding the roll and defining an annular clearance therewith; a transfer opening provided in the roll cover for admitting fiber material to the roll; a waste discharge opening provided in the roll cover for removing waste from the clearance; a fiber removal opening provided in the roll cover downstream of the waste discharge opening as viewed in the direction of roll rotation; an arrangement for generating an air stream for doffing fiber material from the roll and for discharging doffed fiber material through the fiber removal opening; an arrangement for varying a strength of the air stream at the fiber removal opening; and an arrangement for varying the extent of waste removal through the waste discharge opening.
By setting the strength of the air stream for removing the fiber material at the fiber removal opening, it is feasible to improve the waste quality at a separating location situated upstream of the fiber removing location. It is a particular advantage of the invention that an adjustment of the air stream also affects the vacuum between the cover and the roll, and thus the intensity of the removal of foreign bodies at the waste discharge opening is improved. In this manner the ratio between the desired separation of foreign bodies and an undesired separation of good fibers is optimized. It is in particular feasible to ensure, to the extent possible, a minimum loss on good fibers in the foreign body separating process.